Hi Cezza
I ran a marathon in 2003 and I'm currently training for a trail half in June, possible marathon in December. I'm a triathlete so I spend most of my time focusing on that... Anyhoo! Back to your question
All kinds of methods, training plans, and information are available at Runnersworld.com and Active.com/active.
Most slightly aggressive plans start with a base of 20 - 25 miles a week, but it can be done with less. When I ran my first I was running maybe 8 miles a week to start (September) and the marathon was 4 months later in December. Basic things to keep in mind: (1) Run three days a week, one easy run, one speed workout, and one long run. (2) Increase your distance no more than 10% per week. (3) Ease off every 4th week (reduce distance or minutes by 10% per workout for that week) then keep building the next consecutive 3 weeks, etc. (4) Speed workouts don't need to be crazy, but they should push you into your anaerobic threshold and keep you there. Repeats at a given pace, sprints, fartlek and tempo runs are all types of speed work. Oh, and a heart rate monitor will help you big time. I got mine for $50 at Target years ago and it still works.
I hope that helps!
(for the record, I used to have an account here as endurancejunkie but school, getting married, and life got in the way of regular readings/postings. I lost all my login info and had to create a new account. I've done three races this season with A Big One coming up in 2 weeks; then all of my A priority races later summer. Since last time I was here, I've lost 20 lbs, (from 180 to 160), I'm 5'8, I have more body fat that I care to admit to, and a BMI of 24.3. Current goals are faster run splits, better transitions, and to keep on enjoying myself